Numerous devices are currently available to attach objects to bone. More specifically, screws, staples, cement and sutures have all been used to attach soft tissue (e.g. ligaments, tendons, muscles, etc.), bone and inanimate objects (e.g. prostheses) to bone.
In certain situations it is desirable to anchor one end of a piece of conventional suture in bone, leaving the other end of the piece of suture residing free outside the bone so that the free end of the suture can then be used to attach the desired object (e.g. a ligament or prosthesis) to the bone.
Suture anchors for anchoring one end of a piece of conventional suture in bone, and installation tools for deploying the same, are described and illustrated in pending U.S. patent application Ser. No. 051,367, filed 5/18/87 by Roland F. Gatturna et al. for "Suture Anchor", pending U.S. patent application Ser. No. 132,940, filed 12/15/87 by James E. Nicholson et al. for "Suture Anchor Installation Tool", and pending U.S. patent application Ser. No. 308,318, filed 2/8/89 by Roland F. Gatturna.
Still other suture anchors and suture anchor installation tools are described and illustrated in U.S. Pat. No. 4,632,100, issued 12/30/86 to Somers et al., U.S. Pat. No. 4,738,255, issued 4/19/88 to Goble et al., and U.S. Pat. No. 4,741,330, issued 5/3/88 to Hayhurst.
In certain circumstances it may be desirable to have more than one suture end residing free outside the bone for use in attaching the desired object or objects to the bone. In this situation, with the suture anchors of the above-identified pending U.S. Pat. applications Ser. Nos. 051,367 and 132,940, as well as with the suture anchors of the above-identified U.S. Pat. Nos. 4,632,100, 4,738,255 and 4,741,330, the only recourse is to implant more than one suture anchor to provide the desired more than one free suture ends. This technique can have obvious disadvantages.
The above-identified U.S. patent application Ser. No. 308,318 discloses a suture anchor wherein two separate sutures are attached to a single suture anchor, thereby yielding two free suture ends for each suture anchor deployed, but this arrangement requires that two separate sutures be threaded through the anchor's suture-receiving bore and thereafter tied to one another so as to affix the two separate sutures to the suture anchor. This threading and tying operation can be relatively time-consuming to achieve. In addition, this attachment technique creates the additional risk that the sutures can become separated from the suture anchor if the knot should fail.